Final answer:
Hydrogen bonding stabilizes the α-helix and β-pleated sheet structures of proteins.
Step-by-step explanation:
The type of interaction that stabilizes the α-helix and β-pleated sheet structures of proteins is hydrogen bonding. Hydrogen bonding occurs between the backbone atoms of the polypeptide chain and helps maintain the secondary structure of proteins. In an α-helix, hydrogen bonds form between the carbonyl oxygen of one amino acid and the amide hydrogen of an amino acid four residues down the chain. In a β-pleated sheet, hydrogen bonds form between neighboring strands.